In response to demand for video of higher resolutions, Full HD (High Definition) video content of horizontal 1920×vertical 1080 (pixels) has been provided. In addition, test broadcasting and commercial broadcasting of high-definition video of horizontal 3840×vertical 2160 (pixels) (hereafter referred to as “4K”) have been started. Furthermore, commercial broadcasting of high-definition video of horizontal 7680×vertical 4320 (pixels) (hereafter referred to as “8K”) has been planned.
In a video content distribution system, typically, a transmitter encodes a video signal based on the H.264/AVC (Advanced Video Coding) standard or the HEVC (High Efficiency Video Coding) standard, and a receiver performs a decoding process to reproduce the video signal. In 8K, the processing load in the encoding process and the decoding process is high due to a large number of pixels.
As a method for reducing the processing load in 8K, for example, Non Patent Literature (NPLa) 1 describes screen 4-division encoding using slices (see FIG. 11). As depicted in FIG. 12, according to NPL 1, in the case where screen 4-division encoding is used, a motion vector for motion compensation (MC) in a block near a boundary between two slices (a slice boundary) has a constraint that the component in the slice vertical (longitudinal) direction is less than or equal to 128 pixels when performing inter prediction. Meanwhile, a block not belonging to near the slice boundary is not subjected to any constraint (hereafter referred to as “motion vector restriction”) of the motion vector range in the vertical direction across the slice boundary.
For 4K or 8K, the use of not only a video signal of standard dynamic range (hereafter referred to as “SDR”) but also a video signal of Hybrid Log Gamma (hereafter referred to as “HLG”) which is a high dynamic range (hereafter referred to as “HDR”) standard of the ARIB STD-B67 standard, Perceptual Quantizer (hereafter referred to as “PQ”) which is a HDR standard of the SMPTE (Society of Motion Picture and Television Engineers) ST. 2084 standard, and the like is under study. This makes it necessary to take SDR/HDR switching into consideration.